The present invention generally relates to aircraft landing gear. More particularly, the invention relates to landing gear with integrated drive systems to propel an aircraft during taxiing.
A typical aircraft may taxi on to and from runways with thrust force developed by its engines. A significant amount of fuel may be burned by the engines during a typical aircraft taxi profile before and after each flight. In many cases, the main engines may provide more motive force than is required to complete a successful taxi profile. In that regard, engine-thrust taxiing may be considered inefficient and may contribute to high fuel costs and ground level emissions.
Aircraft designers have sought a more efficient method for propelling an aircraft during taxiing. Electric taxi systems (ETS) have been proposed to provide higher efficiency. A typical ETS may be implemented by using electrical motors to drive main landing gear wheels for aircraft taxiing. While this general ETS concept holds promise for improved efficiency, there are practical application problems that need to be addressed. Designers have been faced with the challenge of constructing a main landing gear ETS as a small and light-weight unit which may be positioned on main landing gear without a requirement to substantially modify the operational features or size of the landing gear. Additionally, designers have sought to include multiple operational features into the ETS unit. For example, it has been a design goal to incorporate into the ETS unit a capability for forward and reverse aircraft movement, safe braking after reverse aircraft movement, high torque for initial movement of the aircraft, and high speed for normal taxiing. These design goals relating to a multiplicity of operational features often conflict with the design goal of constructing an ETS unit that is compact and light-weight.
As can be seen, there is a need for an aircraft landing gear wheel-drive system which may incorporate a multiplicity of features such as a capability for forward and reverse aircraft movement, safe braking after reverse aircraft movement, high torque for initial movement of the aircraft, and high speed for normal taxiing. Additionally there is a need for an aircraft landing gear wheel-drive system which may only minimally impact existing aircraft structures and weight, (e.g., landing gear, landing gear doors, and wheel well configuration).